1. Field of the Invention
The present invention relates to a gateway apparatus mounted on a vehicle and relaying data between a plurality of networks, and also to a data managing method with the gateway apparatus.
2. Description of the Related Art
Recently, as shown in FIG. 33, a plurality of ECUs are mounted on vehicles, such as an engine ECU, a door controlling ECU, an airbag ECU, an audio ECU, and a navigation ECU. In order for these in-vehicle ECUs to have communications between a plurality of LANs having different communication systems and different communication speeds, a gateway apparatus is required.
A gateway apparatus implements gateway functions such as relaying data sent and received between a plurality of different networks by software control, conversion of communication protocols, and packet filtering. Thus communications between nodes connected to different networks are performed.
Information sent and received between ECU's is, however, more likely to be increased in amount with a result that there is a problem that processing time for each message and thus the staying time thereof in a gateway apparatus are increased.
In Japanese Patent Application Publication No. JP-A-10-13472, a technology is disclosed for storing a packet as well as a time stamp in a sending buffer, and for discarding the packet if it is a long time between receiving and sending the packet.
In the technology disclosed in Japanese Patent Application Publication No. JP-A-10-13472, time stamps are stored collectively in a sending buffer and a packet is discarded by referring to the time stamp information in the sending buffer when it is necessary.
In a gateway apparatus which has a plurality of communication channels and implements data transfer between the channels, a processing unit provided with each channel refers to a sending buffer, with a result that delay occurs in the processing. When referring to the time stamp, it is necessary for a processing device of each channel to exchange the address information of the sending buffer, with a result that the processing becomes complicated.